Sound processing and stimulation systems and methods for use with cochlear implant devices

Abstract

Sound processing strategies for use with cochlear implant systems utilizing simultaneous stimulation of electrodes are provided. The strategies include computing a frequency spectrum of a signal representative of sound, arranging the spectrum into channels and assigning a subset of electrodes to each channel. Each subset is stimulated so as to stimulate a virtual electrode positioned at a location on the cochlea that corresponds to the frequency at which a spectral peak is located within an assigned channel. The strategies also derive a carrier for a channel having a frequency that may relate to the stimulation frequency so that temporal information is presented. In order to fit these strategies, a group of electrodes is selected and the portion of the current that would otherwise be applied to electrode(s) having a partner electrode in the group is applied to the partner electrode.

1. A sound processing unit for use in a cochlear implant sound processing unit, the unit comprising:
 circuitry for computing a frequency spectrum of a signal representative of sound in order to produce a representation of the signal that is broken down into a plurality of frequency bins that are organized into a plurality of channels such that each channel comprises a subset of the plurality of bins; and 
 additional circuitry being adapted to:
 determine a bin that has the most energy out of a subset of the bins corresponding to a channel included within the plurality of channels; 
 determine whether the energy in the bin is larger than energies in other bins adjacent to the bin; 
 if the energy in the bin is larger than energies in the adjacent bins, compute a stimulation frequency corresponding to the channel to be a frequency that corresponds to a location of a point in the middle of the bin; and 
 if the energy in the bin is not larger than energies in the adjacent bins, compute the stimulation frequency corresponding to the channel to be a frequency that corresponds to a location of a point that lies midway between the bin and another bin having the larger energy of the adjacent bins. 
 
 
     
     
       2. The sound processing unit of  claim 1 , wherein the circuitry for computing the frequency spectrum is configured to apply a Fast Fourier Transform to the signal representative of the sound. 
     
     
       3. The sound processing unit of  claim 1 , wherein the additional circuitry is configured to determine the bin that has the most energy by taking a sum of a square of a real part and an imaginary part of the input signal. 
     
     
       4. The sound processing unit of  claim 1 , wherein the additional circuitry is configured to determine whether the energy in the bin is larger than the energies in the other bins adjacent to the bin by computing a log of the bin and the other bins. 
     
     
       5. The sound processing unit of  claim 1 , wherein the additional circuitry is further configured to translate the stimulation frequency into a cochlear location. 
     
     
       6. The sound processing unit of  claim 5 , wherein the translation comprises interpolating the cochlear location from a frequency-to-location table. 
     
     
       7. The sound processing unit of  claim 5 , wherein the additional circuitry is configured to cause a cochlear stimulator to stimulate a pair of electrodes using relative current weights to stimulate a virtual electrode at the cochlear location. 
     
     
       8. A sound processing unit for use in a cochlear implant sound processing unit, the unit comprising:
 circuitry for computing a frequency spectrum of a signal representative of sound in order to produce a representation of the signal that is broken down into a plurality of frequency bins that are organized into a plurality of channels such that each channel comprises a subset of the plurality of bins; and 
 additional circuitry being adapted to:
 determine a bin that has the most energy out of a subset of the bins corresponding to a channel included within the plurality of channels; 
 determine whether the energy in the bin is larger than energies in other bins adjacent to the bin; and 
 if the energy in the bin is not larger than energies in the adjacent bins, compute a stimulation frequency corresponding to the channel to be a frequency that corresponds to a location of a point that lies midway between the bin and another bin having the larger energy of the adjacent bins. 
 
 
     
     
       9. The sound processing unit of  claim 8 , wherein the circuitry for computing the frequency spectrum is configured to apply a Fast Fourier Transform to the signal representative of the sound. 
     
     
       10. The sound processing unit of  claim 8 , wherein if the energy in the bin is not larger than energies in the adjacent bins, the additional circuitry is further configured to compute the stimulation frequency to be a frequency that corresponds to a location of a point in the middle of the bin. 
     
     
       11. The sound processing unit of  claim 8 , wherein if the energy in the bin is larger than energies in the adjacent bins, the additional circuitry is further configured to compute the stimulation frequency to be a frequency that corresponds to a location of a maximum of a parabola that is fit between a plurality of points within the bin and two of the adjacent bins. 
     
     
       12. The sound processing unit of  claim 8 , wherein the additional circuitry is configured to determine whether the energy in the bin is larger than the energies in the other bins adjacent to the bin by computing a log of the bin and the other bins. 
     
     
       13. The sound processing unit of  claim 8 , wherein the additional circuitry is further configured to translate the stimulation frequency into a cochlear location. 
     
     
       14. The sound processing unit of  claim 13 , wherein the translation comprises interpolating the cochlear location from a frequency-to-location table. 
     
     
       15. The sound processing unit of  claim 13 , wherein the additional circuitry is configured to cause a cochlear stimulator to stimulate a pair of electrodes using relative current weights to stimulate a virtual electrode at the cochlear location. 
     
     
       16. A sound processing unit for use in a cochlear implant sound processing unit, the unit comprising:
 circuitry for computing a frequency spectrum of a signal representative of sound in order to produce a representation of the signal that is broken down into a plurality of frequency bins that are organized into a plurality of channels such that each channel comprises a subset of the plurality of bins; and 
 additional circuitry being adapted to:
 determine a bin that has the most energy out of a subset of the bins corresponding to a channel included within the plurality of channels; 
 determine whether the energy in the bin is larger than energies in other bins adjacent to the bin; 
 if the energy in the bin is larger than energies in the adjacent bins, compute a stimulation frequency to be a frequency that corresponds to a location of a maximum of a parabola that is fit between a plurality of points within the bin and two of the adjacent bins; and 
 if the energy in the bin is not larger than energies in the adjacent bins, compute the stimulation frequency to be a frequency that corresponds to a location of a point that lies midway between the bin and another bin having the larger energy of the adjacent bins. 
 
 
     
     
       17. The sound processing unit of  claim 16 , wherein the circuitry for computing the frequency spectrum is configured to apply a Fast Fourier Transform to the signal representative of the sound. 
     
     
       18. The sound processing unit of  claim 16 , wherein the additional circuitry is further configured to translate the stimulation frequency into a cochlear location. 
     
     
       19. The sound processing unit of  claim 18 , wherein the additional circuitry is configured to cause a cochlear stimulator to stimulate a pair of electrodes using relative current weights to stimulate a virtual electrode at the cochlear location.